Flask cap



FIG. 1 is an upper, front, and left side perspective view of a flask cap showing our new design;

FIG. 2 is a lower, rear, and right side perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

Elements of the flask cap depicted using broken lines are intended to illustrate the environment of the claimed design and form no part of the claimed design. 

CLAIM The ornamental design for a flask cap, as shown and described. 